With casual dating via Tinder you might as well end up dating a serial killer, and even if you don't you still have much harder time really getting to know the person if you don't have any common friends, come from different cities, etc.
A wise man once said "in-laws are never a reason to get married or to not got married"
Also I know of many Pakistani arranged marriages between 1st cousins, it leads to a lot of premature babies. So as with everything there are pros and cons. I am pretty sure that a serial killer, as with most of them, would seem normal and respectable during any family gatherings. It's not like they would be like "ah welcome to my home future life partner, do you want to see my collection of severed hookers heads?"